264
FXUS63 KDVN 190554
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1254 AM CDT Fri Jul 19 2024

.KEY MESSAGES...

- Dry and pleasant summer weather for the rest of the work
  week and into the weekend.

- Very low chance (15-20%) of diurnally driven showers/storms
  Sunday and Monday.

- Moderate to major river flooding continues on the Mississippi
  River. The Rock River to crest in the Moderate category at
  Joslin and Moline by the end of the week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 202 PM CDT Thu Jul 18 2024

Beautiful summer conditions were seen today, with high pressure
overhead. Temperatures at 2pm, were in the middle 70s, with
dewpoints in the 50s making it feel more like September outside!

Tonight...clouds will diminish after sunset tonight, as the surface
high slides east. Another cool night is forecast, with clear skies
and light wind. Overnight lows will drop into the mid 50s.

Friday...weak WAA will commence on the back side of the high. RAP
925-850mb RH progs will rise near 70% suggesting that more fair wx
Cu will develop during the afternoon. Otherwise, another beautiful
day will be seen with highs in the upper 70s/low 80s.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 202 PM CDT Thu Jul 18 2024

While surface high pressure remains in the Midwest through Sunday, a
weak upper low is forecast to slowly drop into the Plains, and shift
east into Iowa for Sunday and Monday, as it weakens. At the very
least, this will allow for more of a diurnal increase in cloud cover
each day, but should also allow for a isolated to scattered shower /
storm chance.  The flow aloft will be weak, and moisture depth
appears limited. Thus, these pop/drop showers should not move
quickly, and would only offer an isolated rainfall potential. Taking
a look at the model ensembles, the probabilities of any measurable
rain through 18z Sunday is less than 40%, with the highest values in
the far western counties. The GEFS is the wettest and the 12z GFS
deterministic run remains in this camp.

Temperatures will be warming only modestly through the period, with
dew point temperatures rising to only the lower to mid 60s, which is
largely driven by evapotranspiration as opposed to moist advection.
Highs in the lower to mid 80s are forecast Monday through Thursday.
Lows in the lower to mid 60s are expected.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1250 AM CDT Fri Jul 19 2024

VFR to continue through the period with light winds and unrestricted
visibility.

&&

.HYDROLOGY...
Issued at 1125 AM CDT Wed Jul 17 2024

The Mississippi River has crested at all sites, with some reaches
continuing to experience somewhat stalled falls or steady trends
over the next few days due to recent bouts of heavy rain, local run-
off, and tributary input. L&D 19 at Keokuk and Gregory Landing will
even experience secondary rises into the weekend.

Tributary Rivers:

The recent rounds of heavy rain on the Rock River basin will
continue to produce significant rises on the Rock, but after
assessing the extent of run-off and upstream flow trends, Joslin and
Moline are now projected to remain below the Major flood stage. The
Rock at Como will be in Minor flood through Friday evening.

The Pecatonica River is projected to rise into Minor flood at
Freeport IL Friday night.

The lower Wapsipinicon River near Dewitt, IA performed a secondary
crest around 11.2 feet yesterday/Tuesday evening, but is now
dropping below flood stage. With the dry weather into the weekend,
the Wapsi is now expected to remain in the decline mode and remain
below the flood stage.

Backwater effects from the Mississippi River will keep the lower
Iowa River just below flood stage through early next week.

Further south, torrential rainfall and run-off from Monday night may
produce a large rise to action stage on the La Moine River near
Colmar in west central IL by Thursday. But the extent and speed is
still somewhat uncertain and will have to watch river rise trends
over the next 24 hours.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...Gross
LONG TERM...Gross
AVIATION...Uttech
HYDROLOGY...12